As an example of an automatic machine system such as a production facility or a production line to which a mechanism part including a motor drive shaft is applied, there is a system for performing work such as welding or cutting by applying an industrial robot. There is also a scaled-up robot system with the scale of its production facility varying with the shape or size of a workpiece and including a plurality of robots, a travel mechanism for mounting a robot and traveling or a workpiece moving mechanism for rotating and tilting a workpiece, where a plurality of mechanism parts are coordinated with each other to perform work. To eliminate waste in coordinated operation between mechanism parts, the operations of these mechanism parts are controlled by a single controller.
A robot system includes a control part (controller) for controlling the operation of a mechanism part such as the robot and a portable teaching operation part (also called a pendant) carried along by a worker for example in the teaching work for registering and changing a work procedure as a work program.
The teaching operation part is used also for teaching a plurality of robots or other mechanism parts to teach various work programs of individual robots and mechanism parts before the system starts running. For this purpose, a desired mechanism part is specified from among a plurality of mechanism parts such as robots prior to teaching work.
An exemplary block diagram of a related art robot system is shown in FIG. 5. In FIG. 5, a numeral 101 represents a first robot, 102 a second robot, 103 a controller for controlling the operation of the robots 101 and 102, 104 a portable teaching operation part, 105 a complex cable for transmitting information such as a push on an operation button or an emergency shutdown between the controller 103 and the teaching operation part 104 or supplying power.
A detail plan of the teaching operation part 104 is shown in FIG. 6. In FIG. 6, a numeral 104a represents an almost T-shaped enclosure and 104b a hand part grasped by the worker. On the operation surface of the enclosure 104a are arranged a keyboard (or keysheet) 104c operated in teaching, an LCD display 104d for displaying various information such as teaching data and robot position, and an emergency shutdown switch 104e (corresponding to emergency shutdown means). To the enclosure 104a is connected one end of the cable 105.
The worker wishing to operate the first robot 101 must previously select the first robot 101 in the operation on the teaching operation part 104. When the worker presses the direction key of each robot axis on the keyboard 104c, axis operation information is transmitted to the controller 103 via the cable 105. The controller 103 outputs a drive current to a drive axis motor (not shown) of the first robot 101 to operate the first robot 101. The direction key refers to a key used to instruct the operation direction of a motor, direction in the Cartesian coordinates or operation direction of a robot wrist in the teaching work or the like.
Similarly, when the worker presses the emergency shutdown switch 104e, emergency shutdown information is transmitted to the controller 103 via the cable 105. The controller 103 shuts down power to the drive motor (not shown) for the robots 101, 102 and applies a brake (not shown) to each drive axis motor to forcibly stop the operation of the robots 101, 102. This reliably brings a robot in emergency shutdown upon possible unintended operation.
When performing teaching work concerning registration and change of a work program using the first robot 101, the worker performs programming of the work program and position registration of the first robot 101 via operation on the teaching operation part 104. For the position registration of the robot, the first robot 101 is moved to a desired position by way of a push on the direction key of each robot axis on the teaching operation part 104 and the position of the robot 101 is registered via registration operation on the keyboard 104c. To change the registered position, the first robot 101 is moved to a desired position by the same operation and the new position is registered via position change operation.
As an exemplary technique to select a desired mechanism part (robot), Patent Reference 1 discloses a controller which selects, in the procedure for manually operating a single robot alone among a plurality of robots connected to a single controller, a robot to be instructed to operate with the operation of a target device selector switch on a teaching pendant (teaching operation part) connected to the controller and which checks the correspondence between a number selected and the actual robot selected in accordance with the state of an indicator lamp arranged on the robot or close to the robot.
Patent Reference 2, similar to Patent Reference 1, discloses that a ten-key pad or the like functions as a selector switch for specifying a particular manipulator (robot) from among a large number of manipulators (robots).    Patent Reference 1: JP-A-05-173627 (refer to line 37 and thereafter, Section 4 and line 44 and thereafter, Section 5)    Patent Reference 2: JP-A-05-127734 (refer to line 21 and thereafter, Section 3)